Heat transfer equipment of the tube and header coil type



1941- J. w. THROCKMORTON 2,260,243

HEAT TRANSFER EQUIPMENT OF THE TUBE AND HEADER COIL .TYPE

Filed Oct. 17, 1940 \lw/z iq aq yo ra/ w, W UM,

Patented "Oct; 21, 1941 HEAT TRANSFER EQUIPMENT OF THE TUBE 7 AND HEADER 0011. TYPE John W. Throckmorton, Wilton, Conn, assignor to Petro-Chem Development Company, New York, N. Y., a corporation of Delaware,

Application October 17, 1940, Serial No. 361,516

1 Claim.

the return headers or fittings are disposed at the outer sides of such sheets.

It is also usable in connection with such equipment applied to tar coolers, drip condensers, and the like, wherein merely a rack or frame work for carrying the weight of the tubes and headers and to maintain the proper spacing may be employed in place of tube sheets.

In the use of heat transfer equipment of this type, it is necessary to arrange the coil tubes and headers or return bends so that they may be properly inspected and cleaned. The oil may corrode such parts, and it is therefore imperative that means of inspection and measurement thereof be provided. The coils may also become clogged with coke formed in the refining process, and this makes it necessary to provide a convenient means for permitting the removal of this coke at the cleaning and inspection periods.

In the designing and useof convection banks of furnaces, as well as other types of tubular heat transfer equipment, it is recognized that it is often very desirable to have-a high mass velocity over the outside of the tubes which may be accomplished by placing the tubes on close centers. With such close centering'it is not only possible, under certain conditions, to increase the mass velocity over the heating elements, but also to I increase the transfer rate per degree of mean temperature difference, and reduce the amount of I centering of, the tubes than is now possible or practicable, so that the advantages incident to for the efiicient, convenient and proper cleaning out and inspection of the coil tubes and connected headers or return bends of such equipment without interfering with or preventing the close tube centering feature of the inventions A further object of the invention is to so construct the header or return bend and connect the tubes of-a pipe coil thereto as to cause a true, smooth streamline flow through the header and past the tube joints therewith, so as to reduce to a minimum turbulence of the stream in its passage through the header past the points of jointure of the tubes therewith, thereby materially reducing objectionable corrosion and pressure in the equipment at such points.

Other objects and advantages of the invention will be apparent from the following detailed description, and from the accompanying drawing illustrating the invention, in which--- 7 Figure 1 is a portion of a pipe coil including afplurality of connected tubes and headers, embodying the invention, and with the header or return bends disposed without the tube sheets; Fig. 2 is an enlarged central vertical section taken lengthwise of/a header'like shown in Fig. 1, with two tubes connected thereto, one being rolled and the other welded; Fig. 3 is a central cross-section on .theline 33 in Fig. 2. s

In the drawing, the pipe coil is shown as being composed of a plurality of tubes l disposed in transversely spaced parallel relation and con-. nected in pairs at their ends by headers or return bend fittings 2, so as to'form-a continuous 'coil. through which oil or other liquid being treated may be circulat as being supportedin 'ube sheets 3 and the fittings 2 a e disposed without such sheets. In this form f the invention, each header 2 preferably has a welded connection 4 with one tube, preferably the inlet tube with respect to such header, and a rolled connection, 5 with the other tube, and the clea -out opening 6 for the header,

fore it has been the practice, so far as I am aware,

to connect the tubes to the headers by rolling. It

is found, .however, that materially closer tube centers can be obtained if, in connecting a ,pair

of'tubes to a header or return bend, one

connected to theheader by a rolled joint and the other by a welded joint, thus enabling the'centers the rolled joint.

A further object of the invention is to provide 55 only one of which is provided, is disposed in substantially coaxial, alignment with the rolled-in joint. With this arrangement it is apparent that each tube has a welded connection at one end and a rolled in connection'at the other end with the respective headers. t

It will be noted'by reference to Fig. 2 that in thlilslt form of'header, the disposition of the welded 3 end of the passage through the header to provide a slrrooth, streamlined flow without any interrupting joint and that shoulders, recesses and pockets tending to cause turbulence of the stream drop . The tubes I are shown at the outlet side of the header enables such are disposed only at the inlet side of the header passage and at its point of rolled-in connection with the outlet tube. It is found in practice that where a header has rolled connection with both pipes of a pair the most severe corrosion takes place at the inlet end of the pipe and that such. corrosion is negligible at the outlet end of the pipe; also, that, if the inlet end of the tube is welded to the header, the high turbulence and consequent corroding 'action and drop in pressure of the stream due to the rolled joint will be avoided and a. smooth streamline flow obtained. This advantage is augmented by providing the header with a single cleanout opening which is disposed in line with the rolled-in tube at the inlet end of the header (the outlet end of the tube).

The cleanout opening 6 may be closed by a plug I held in seated position in any suitable manner, for instance by a screw 8 threaded through a cross member 9 removably anchored in openings provided in transversely opposedupright ears III on the header. The provision of to support welding than is required at the other end to withstand the strains incident to rolling in of the tube. By reason of this closer centering of the tubes in the header, it is possible to increase the mass velocity over the heating elements, thereby increasing the transfer rate per degree oi mean temperature difference ous modifications and changes without departing from the spirit of the claim.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent, is:

In a heat transfer 0011 of the type set forth, wherein a pair of tubes are interconnected, a substantially U-shaped tubular header for interconnecting the tubes, one leg of the header being of a length greater than that of the other and extending outwardly beyond the curve of the header for a distance suflicient for having a rolled joint connection with one of the tubes, and the other and shorter leg terminating at its inner end intermediate the ends of the first leg and closely adjacent tothe curve of the header and bein welded to the other tube, said header having a single access opening in alinement withvthe first mentioned tube whereby to lessen the material at the welded end of the header and thereby provide closer centering of the connected tubes, and increase of the mass velocity of the heating elements.

JOHN W. THROCKMORTON. 

